DE-A1-199 60 642, which forms the genus, describes a pyrotechnic detonator with an igniter support of plastic. An igniter element is integrated into the igniter support, and its active part protrudes from the igniter support and reaches into a metal case which is fastened to the detonator holder. A booster charge is contained in the metal case.
The igniter support of plastic serves the purpose of fixing the ignition element in the metal case in a mechanically secure manner. In addition, it must assure that, when the detonator operates, no gas can escape between the plastic igniter support/ignition element and/or the plastic detonator holder/metal case.
On account of the need for mechanical strength in the operation of the detonator, in conjunction with the complex form in the contacting area of the ignition element, the igniter support has heretofore been made by machining as a combination turning and milling part. This method of manufacture is very cost-intensive.
The invention addresses the problem of improving a pyrotechnic detonator with respect to its sealing and its manufacturing costs.
This problem is solved according to the invention by integrating a metal insert in the igniter support for mechanical support, the metal insert being embedded in the plastic of the igniter support.
In preferred embodiment the metal insert is a stamped part or is made by bending.
Advantageously the plastic of the igniter support is doped with mica.
The ignition element is partially or entirely encased in plastic.
It is appropriate to wet the ignition element with a sealing composition before it is encased in plastic.
In certain areas an elastic synthetic material can be used as plastic for the igniter support.
In a preferred embodiment the metal insert is bonded with the ignition element. Thus only a portion has to be encased in the plastic.
Advantageously, the metal insert is cup-shaped, the margin of the metal insert being beaded or folded over, and is brought out from the igniter support.
For better bonding with the plastic, holes are advantageously provided in the metal insert.
The invention is characterized in a preferred embodiment by the fact that, instead of complicated machining, a stamped and bent piece is used which is then encased as an insert.
This manner of manufacture is very economical, since both the insert and the subsequent injection molding process can be performed at low cost. Both manufacturing methods can be practiced with multiple tools, resulting in an additional cost reduction.
In this arrangement the metal insert or stamped or bent piece provide the mechanical support which can be made with equal strength and less wall thickness due to their stiffness than a turned or milled part. Thus a saving of weight can additionally be achieved.
The plastic in the igniter support assures the seal between the igniter support/ignition element and/or igniter support/metal case. The necessary complex shape in the contact area of the ignition element can likewise be achieved with the plastic by the injection molding process.
In practice, it has developed in the conventional igniter supports that, due to stray conductive impurities, e.g., metal chips, an unwanted electrical connection can develop in the contact region between the ignition element and the igniter support which can result in failure of the detonator to operate. In the case of a plastic igniter support such electrical connections cannot develop since it insulates in the contact area.
To increase safety against electrostatic discharges (ESD) between the ignition element and the metal casing, the plastic of the igniter support can be doped with mica. This results in a high-resistance plastic that develops low resistance at high voltage, and bleeds off the ESD discharges so that no unintentional firing takes place.
Additional features of the invention are shown by the figures, which are described below.